• Journal of the Korea Institute of Military Science and Technology
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• v.21 no.1
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• pp.17-24
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• 2018

Polar fomat algorithm (PFA) was derived from medical imaging theory, known as back projection, to process synthetic aperture radar(SAR) data. The difference between the operating condition of SAR and back projection assumption makes two distortions. First, the focusing performance of PFA is degraded in proportion to distances from the scene center. Second, the geometric accuracy in SAR images is distorted. Several methods were introduced to mitigate the distortions, but some disadvantages, such as the geometric discontinuity, are arisen when sub-images are combined. This paper proposes the novel method to compensate the geometric distortion with chirp Z-transform (CZT). This method corrects precisely the geometric errors without any problems, because a whole image can be processed all at once.

• Journal of Institute of Control, Robotics and Systems
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• v.3 no.3
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• pp.227-237
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• 1997

Autonomous Underwater Vehicles(AUVs) have become an important tool for various purposes in subsea: inspection, recovery, construction, etc., and the development of autonomous control system is luglay desirable- thete zffe many problems associated with designing the control system for AUV due to unknown underwater envimn-Tnent, the possibility of subsystem failures, and unpredictable changes in the dynamics of the vehicle. In this paper, an autonomous control system based on the intelligent control theory to enhance operation efficiency of the ALTV is presented. The control system has a hierarchical structure which consists of mission planning level, mission control level, navigation level, and execution level. The performance of the control system is investigated by computer simulation. The results show that the proposed control system can be applied successfully to the AUV in spite of the possibility of failures in the vehicle and the collision hazard in the sea environment.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.7
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• pp.1078-1082
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• 2017

This paper presents an L1 optimization based filtering technique which effectively eliminates the optical misalignment effects encountered in the squint guidance mode with strapdown seekers. We formulated a series of L1 optimization problems in order to separate the bias and the gradient components from the measured data, and solved them via the alternating direction method of multipliers (ADMM) and sparse matrix decomposition techniques. The proposed technique was able to rapidly detect arbitrary discontinuities and gradient changes from the measured signals, and was shown to effectively cancel the undesirable effects coming from the seeker misalignment angles. The technique was implemented on embedded flight computers and the real-time operational performance was verified via the hardware-in-the-loop simulation (HILS) tests in parallel with the automatic target recognition algorithms and the intra-red synthetic target images.

• Journal of the Korea Institute of Military Science and Technology
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• v.19 no.2
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• pp.163-170
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• 2016

Tropospheric delay is one of the largest error source in pseudolite navigation system. Because a pseudolite is installed on the ground and transmits its signal to a user in the air or on the ground, the conventional tropospheric delay model developed for a satellite navigation doesn't work properly. In this paper, performance analysis of several pseudolite tropospheric delay models has been done using meteorological data. Based on the result, a new compensation method for Hopfield model has been proposed.

• 한국IT서비스학회:학술대회논문집
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• 2005.11a
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• pp.585-591
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• 2005

참여정부가 정부혁신 방안의 하나로 추진하고 있는 성과관리제도는 조직이 지향하는 목표를 체계적으로 관리하기 위한 것으로, 성과목표를 설정하고 목표 달성 여부를 판단하여 결과를 의사결정에 환류하는 경영관리기법이다. 현재 시행되고 있는 공공분야의 성과관리제도는 정부업무평가, 직무성과계약제, 재정사업 성과관리제도 등 다양하다. 국방부는 정부 방침에 따라 성과관리체계를 구축함에 있어 내부의 성과관리뿐만 아니라 외부 평가제도를 지원하기 위한 통합성과관리체계를 구축하였다. 본 논문에서는 국방부 정보화기획관실의 BSC 기반의 성과관리체계 구축 사례를 통하여 공공기관 정보화조직의 성과관리체계 구축 방향을 제안한다.

• Korean Journal of Remote Sensing
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• v.22 no.3
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• pp.229-234
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• 2006

In tactical theater, it is crucial to detect ground moving targets and to locate them precisely. This problem can be resolved by using SAR (Synthetic Aperture Radar) sensors providing GMTI (Ground Moving Target Indication) capability. In general, to implement a robust GMTI sensor is not simple because of the strong competitions between target signals and clutter signals from the ground, and low speed of moving targets. Contrary to the case that a delay canceller is mostly suitable for ground surveillance radars, DPCA (Displaced Phase Centered Antenna) or STAP (Space Time Adaptive Processing) techniques have been widely adapted for GMTI function of modern airborne radars. In this paper, a new scheme of DPCA using two passive antennas with vertical separation is proposed, which also provides good clutter cancellation performance. The proposed scheme realizes full azimuth coverage for DPCA operation on an airborne platform, which is impossible with classical DPCA configuration. Simulations using various conditions have been performed to validate the proposed scheme, and the results are acceptable.

• Journal of Power Electronics
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• v.19 no.2
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• pp.602-611
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• 2019

The major drawbacks of magnetic resonant coupled wireless power transfer (WPT) to the embedded sensors on spindles are transmission instability and low efficiency of the transmission. This paper proposes a novel double-loop coil design for wirelessly charging embedded sensors. Theoretical and finite-element analyses show that the proposed coil has good transmission performance. In addition, the power transmission capability of the double-loop coil can be improved by reducing the radius difference and width difference of the transmitter and receiver. It has been demonstrated by analysis and practical experiments that a magnetic resonant coupled WPT system using the double-loop coil can provide a stable and efficient power transmission to embedded sensors.

• Journal of Aerospace System Engineering
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• v.14 no.6
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• pp.10-17
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• 2020

The Korean medical evacuation helicopter was developed based on the Korean Utility Helicopter (hereafter referred to as 'Surion'). It uses an auxiliary power unit and engine for heating during winter operation. The helicopter maintains the internal temperature of the aircraft using its bleed air to satisfy its operational capability. However, due to the air inflow through the gap between the aircraft skin and door, additional heating for operating the portable medical equipment and preventing hypothermia in evacuated patients is required. Accordingly, an electric auxiliary heater was developed for additional heating during winter operation, and environmental, durability, and performance tests were conducted per MIL-STD-810G and MIL-STD-461F. The auxiliary heater was verified per the tailored airworthiness certification criteria.

• Journal of the Korea Institute of Military Science and Technology
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• v.4 no.2
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• pp.97-104
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• 2001

Performance specifications leave out unnesessary “how to” or detail and give the manufacturer latitude to determine how to best meet our stated needs. This will increase MND's access to commercial, state-of-the-art technology. However, we find that it is too early to expand the use of performance specification due to the poor domestic infrastructure. To expand the use of performance specification in defense area, this paper suggests the basic principles about which items we should select and which procedeure we should follow.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.231-236
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• 2003

This paper presents a simple approach on the rotational motion estimation and correction for the roll stabilization of the sight system. The algorithm first computes the rotational center from the selected local velocity vectors of related pixels by least square methods. And then, rotational angle is found from the special subset of the motion vector. Finally, motion correction is performed by the nearest neighbor interpolation technique. In order to show the performance of the algorithm, the evaluation for the synthetic and real image was performed. The test results show good performance compared with previous approach.